A wide family of layered van der Waals (vdW) materials can be mechanically isolated down to atomically-thin crystals. Crystals of different materials can then be stacked upon one another to create vdW heterostructures. The electronic properties of these composite structures can be fundamentally distinct from their parent crystals owing to electronic hybridization between the layers.

Upon stacking crystals with a slight lattice mismatch or with a twist angle between layers, an emergent geometric interference pattern — known as a moiré pattern — can act as a long-wavelength synthetic superlattice. This moiré superlattice can strongly modify the band structure of the composite material. Most spectacularly, recent work has shown that moiré patterns in numerous vdW heterostructures can drive very flat electronic dispersions with non-trivial band topology.

Twisted graphene heterostructures have proven to be a fantastic platform for investigating the correlated states — including superconductivity and correlated insulating states — which emerge as a consequence of the moiré superlattice. Furthermore, they are also capable of hosting tunable topological states with ferromagnetic ordering. A variety of other vdW heterostructures are now emerging with similar capabilities. Research in our group focuses on the investigation and control of these exotic electronic states in vdW heterostructures using quantum transport measurements at low temperatures and in high magnetic fields.